Devices for measuring lung volume capacity and for exercising the lungs through breathing exercises have been known for some time. Examples of such devices are shown in U.S. Pat. Nos. 393,869, 515,637, 793,177, 1,926,748, 2,100,898 and 3,695,608. The devices disclosed in the aforesaid patents are operated by the patient or user forcing air out of the lungs into the device. Breath control or lung exercise is achieved by varying the resistance to discharge of the air through the device.
More recently, it has been observed that for patients suffering from diseases which restrict the lung volume capacity, such as bronchitis, emphysema, and the like, and for a condition known as atelectasis, lung volume capacity is best expanded by exercises in which a patient inhales, rather than exhales, as taught in the aforesaid prior art. Moreover, for increasing patient exercise incentive, a device preferably incorporates visual means for the patient to observe success or achievement during the exercise, and means for varying the difficulty of the exercise. It is to such a device that the present invention is directed.